Types of Construction Joints

The fundamental nature of construction is joining one piece of wood to another, using one of several joints that are commonly used to accomplish this task. Edge-gluing can help strengthen joints, but should not be expected to make badly fitting joints secure properly. You also take into account the grain and texture of the wood pieces when constructing joints to fit together.

Overlap Joint

The simplest kind of construction joint to make is the overlap joint. This is accomplished by cutting the boards to length and then placing one board over the other, usually at a right angle. Strengthening an overlap joint is essential; while it is the easiest to make, it is also one of the weakest. Screws and glue are much better choices for securing an overlap joint than nails.

Butt Joint

The butt joint is one of the fundamental ways of connecting wood pieces together. In a butt joint, one piece of wood is designed to squarely fit against another and will be secured by nails, screws, pins, braces or adhesive. While a butt joint is among the easiest to make, it suffers from being one of the weakest types of joints, so ensure that it is well secured.

Lap Joint

Lap joints consist of two pieces that are notched so that one fits on top of the other. This forms a double layer that provides more strength than the butt joint. A key to making a lap joint is ensuring that the notches run across the grain of both pieces of wood. You also want to make sure that the fit is not too tight because this will cause more stress than the joint can take.

Mortise and Tenon Joint

Mortise and tenon joints are the most commonly used when making furniture because they are strong enough to withstand weight and movement. The mortise is the name given to a hole in one piece of wood while the tenon is the part of another piece of wood that sticks out and fits into the mortise. The tenon needs to be one-third the thickness of the board, and the depth of the tenon should match the thickness of the board to which the tenon is going to be attached.

Dovetail Joint

Dovetail joints result in fan-shaped segments on one piece of wood that fit into matching pins on another piece of wood. The ornamental design makes this a good joint for decorative applications like toy chests or cabinets. Dovetail joints are also strong. Dovetail joints can be cut with a router and template, but you can achieve a much more decorative effect when you cut them by hand. The router will make the job faster.